Super Onion Boy is a side-scrolling platformer designed with a classic adventure story and arcade-style graphics and sounds. The main character, Super Onion Boy, must save the princess from enemies who captured her inside a magic bubble while they were walking together. The player helps the hero perform a wide range of actions to earn points, defeat enemies during the journey and collect coins, stars, extra lives and power potions.
The game features a variety of natural environments across 15 levels. Play starts in the Green Forest. Over time, the player helps the character explore other regions, including Crab Island, Sky Mountain, Green Jungle, Desert Hill and Dark Mountain. A timer counts down during play. Additionally, the character receives a limited number of lives. The player must help him walk, jump, leap, drop and float to bypass, knock away or eliminate enemies, including carrots that can knock him from platforms, radishes with jetpacks that pop up from pipes in the ground and happy oranges that roll around like boulders.
Super Onion Boy gives the player access to superpowers for the title character via potions. The character can throw small fireballs, use bubbles to float instead of drop through the air, and set up a diamond-sparkling shield of invincibility.
The player also directs the character to explore underground caverns and teleport to other regions via the pipes. They must watch out for enemies and traps in these areas as well, including bats, crabs, and stationary and falling spikes.